Mystery Cap and Strange Noise

[matt59]

Hi Folks

I have a 1993 ATX.

I'm curious what the little black cap is on top of the throttle body?
I did remove it and there was a ****** on it that had vacuum.

Just by co-incidence I have a strange Humm or a "tiny horn tooting" when the engine is warm and only with the throttle 100% closed.

When I had the little black cap off the noise went away, when I plugged the vacuum leak the noise came back.

Any Ideas? It's annoying when I'm cruising behind someone walking and they turn around look at me like I'm honking at them.
I've even had to follow thru with a "GET THE F*#K OUTTA MY WAY" just so they didn't think my car was a peice of escriment.

Help! I'm not looking for a fight.

 

[khanartist]

My old 93 ATX had the "tiny horn tooting" syndrome as well. Never quite figured out what it was........it happend usually at very slight throttle, or idle....

 

[NoSlo]

noise from intake

The woooo noise seems to come from the flex tube between the MAF (the air filter assembly) and the throttle body, if the position is just right. Loosen both ends of the tube and turn/twist it an eighth of a turn and tighten it back up. That will probably make the sound go away.

 

[Rockledge]

I know this may sound strange, but a funky IAC can cause weird noises like that, even though the noise may sound like its coming from down by the air filter box.

 

[LOUDSHO92]

That ****** is to check your fuel pressure.

You should come to a SHOCal meet!

 

[matt59]

That ****** is to check your fuel pressure.

You should come to a SHOCal meet!

The ****** I'm refering to is not threaded and is on the T/B very close to the IAC,
I Would like to go to the meet as soon as I get my car in reliable condition :cry: .

Once again when I hit 6k rpm the front seal started leaking oil :cuss: of course dripping on the cat and smoking badly.

There is no blowby detectable from the crank case so my guess is the oil pressure against the seal is blowing it out.

What do you think?

 

[SHOZ123]

That cap is used to seal the IAC after it is assembled. Some Ford IACs give funny sounds when they operate.

 

[Orkin]

Mine used to make a humming sound. New IAC = no hum. Not sure if it was worth the trouble, as it doesn't seem to affect drivability/performance at all, and the hum was only barely noticable.

 

[matt59]

The IAC was the problem, I dropped some **** in the ****** ( ) that had the vacumm and the noise went away.
I guess it was just getting stuck or something.

Thanks for the input.